feat(vmm): enable the QMP socket by default

CHANGELOG.md

@@ -7,6 +7,9 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Changed
+- vmm: `qmp_socket` now defaults to `true`. Each CVM's QEMU exposes `qmp.sock` in its work dir, so the host can change disk options or compact a bloated `hda.img` (`blockdev-mirror`) without stopping the CVM. Applies to CVMs started after the change; set `qmp_socket = false` to opt out
+
 ## [0.6.1] - 2026-10-12
 
 dstack 0.6.1 is a security release. Upgrade the guest OS, KMS, and verifier.

docs/tutorials/vmm-configuration.md

@@ -113,7 +113,7 @@ cid_start = 1000
 cid_pool_size = 1000
 max_allocable_vcpu = 124                        # Adjust: total cores - 4
 max_allocable_memory_in_mb = 990616             # Adjust: total MB - 16384
-qmp_socket = false
+qmp_socket = true
 use_mrconfigid = true
 qemu_pci_hole64_size = 0
 qemu_hotplug_off = true

dstack/crates/dstack-cli-core/src/config.rs

@@ -340,7 +340,7 @@ cid_start = {cid_start}
 cid_pool_size = {cid_pool_size}
 max_allocable_vcpu = 20
 max_allocable_memory_in_mb = 100_000
-qmp_socket = false
+qmp_socket = true
 user = ""
 use_mrconfigid = {use_mrconfigid}
 qemu_pci_hole64_size = 0

dstack/vmm/vmm.toml

@@ -43,8 +43,9 @@ cid_start = 1000
 cid_pool_size = 1000
 max_allocable_vcpu = 20
 max_allocable_memory_in_mb = 100_000 # MB
-# Enable QMP socket
-qmp_socket = false
+# Expose a QMP socket (qmp.sock in each VM work dir) for host-side runtime
+# operations such as live disk migration
+qmp_socket = true
 # The user to run the VM as. If empty, the VM will be run as the current user.
 # Unique namespace when multiple dstack-vmm instances share one host. When
 # empty, a stable value is derived from run_path. It is what netd records on